[opendtv] Carve up unlicensed bands, says WiMedia chief
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 13 Dec 2007 17:38:47 -0500
Looks like UWB is redefining itself into something for lower bit rates,
to carry only compressed video. So much for that bit of hype, eh?
Bert
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Carve up unlicensed bands, says WiMedia chief
Rick Merritt
(12/13/2007 10:49 AM EST)
URL: http://www.eetimes.com/showArticle.jhtml?articleID=204802665
SAN JOSE, Calif. - To avoid a fight over bandwidth in unlicensed
frequencies, the industry needs to carve up spectrum bands based on what
applications best fit in them, said Stephen Wood, president of the
WiMedia Alliance.
Wood made his pitch in an interview at a time when members of the
alliance backing wireless USB are under fire for delivering low data
rates and the alliance is gearing up work on 60 GHz radios.
"There's a tendency to bolt into a new place and hope for the best, but
as an industry we need to do an analysis," Wood said. "We suspect the
industry needs to divvy up applications into the various unlicensed
bands. We should do a careful analysis of this situation," he added
The WiMedia Alliance has already approached one university to research
the issue. The group defined an ultrawideband technology that is the
basis for wireless USB and is helping define a standard for 60 GHz
radios as well.
An independent lab recently reported the initial products using wireless
USB have data rates of no more than 50 Mbits/s, far below the
theoretical 480 Mbits/s claimed for USB. Woodwas quick to point out the
external devices tested were aimed at relatively low-end uses.
"If you are trying to support printers and scanners 50 Mbits/s is
adequate," said Wood of WiMedia.
In addition, the external devices carry overhead because they must
translate a wired USB signal to wireless and back again to a wired link.
Systems with wireless USB on mini-PCI cards embedded in notebooks don't
face that hurdle and thus hit rates as high as 160 Mbits/s in recent
public demonstrations, Wood said. When devices at both end of a link use
native, embedded chips rates will go as high as 220 Mbits/s, he added.
The wireless USB protocols also came in for a thrashing for slowing down
the underlying capabilities of UWB radios. "The protocols stacks can
have legacy support and a more general purpose nature which creates
overhead, and implementations vary by vendors," said Wood.
"People have been saying the USB protocols are not friendly for
wireless, they are too chatty and that impacts data throughput and power
consumption," said Mike Foley, executive director of the Bluetooth
Special Interest Group.
Nevertheless, "people are still optimistic [the underlying UWB radio]
can meet our bandwidth requirements" of 100 Mbits/s for a proposed
Bluetooth version 3.0 which specifies operation at 6 GHz and up, Foley
said.
Three chip makers showed data rates of 175 Mbits/s or more at 6 GHz and
above at a Bluetooth SIG meeting in Beijing in September, said Wood. In
a more recent demo in Silicon Valley WiQuest showed data rates up to 375
Mbits/s using a proprietary protocol geared for video, Wood added.
Nevertheless the WiMedia Alliance is working with the Ecma International
standards group to finish by this summer a standard for 60 GHz radios.
WiMedia will develop interoperability tests for the standard which Wood
said is well suited to carrying uncompressed video just as wired HDMI
does today.
"We expect WiMedia members to build 60 GHz radios and talk to users of
DisplayPort about using the radios for wireless," Wood said. "But we
don't expect this technology to mature for three years or more," he
added.
Wood suggested 60 GHz radios are best for carrying uncompressed video
while UWB could serve compressed video. That would leave few video apps
for Wi-Fi, a rival technology.
All material on this site Copyright 2007 CMP Media LLC. All rights
reserved.
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